Vehicles may be powered by an engine and/or one or more batteries. For example, the engine may provide motive power for the vehicle and/or charge the batteries. The batteries, in turn, may provide power for starting the engine and vehicle accessories, and/or may provide motive power for the vehicle.
Both engines and batteries may produce a large quantity of waste heat, i.e., excess thermal energy, during operation. Therefore, engines and batteries are often cooled with a coolant to remove excess thermal energy through heat exchange and dissipation to the atmosphere. Despite improvements in engine and combustion technology, nearly one-quarter of fuel energy may be expelled as waste heat during operation of the engine and/or batteries. Therefore, significant gains in vehicle fuel economy may be realized if waste heat is converted into usable mechanical and/or electrical energy.